<template>
    <div class='xtx-carousel' @mouseenter="stop()" @mouseleave="start()">
        <!-- 轮播图 -->
        <ul class="carousel-body">
            <li class="carousel-item" v-for="(item, i) in sliders" :key="i" :class="{ fade: index === i }">
                <RouterLink to="/">
                    <img :src="item.imgUrl" alt="">
                </RouterLink>
            </li>
        </ul>
        <!-- 左侧上一页 -->
        <a href="javascript:;" class="carousel-btn prev" @click="toggle(-1)"><i
                class="iconfont icon-angle-left"></i></a>
        <!-- 右侧下一页 -->
        <a href="javascript:;" class="carousel-btn next" @click="toggle(1)"><i
                class="iconfont icon-angle-right"></i></a>
        <!-- active激活 -->
        <div class="carousel-indicator">
            <span @click="index=i" v-for="(item, i) in sliders" :key="i" :class="{ active: index === i }"></span>
        </div>
    </div>
</template>
  
<script>
import { ref, watch } from 'vue';


export default {
    name: 'XtxCarousel',
    props: {
        //轮播图所需数据
        sliders: {
            type: Array,
            default: () => []
        },
        //自动播放
        autoPlay: {
            type: Boolean,
            default: false
        },
        //间隔时间
        duration: {
            type: Number,
            default: 3000
        }
    },
    setup(props) {
        const index = ref(0)
        // 自动播放函数
        let timer = null
        const autoPlayFn = () => {
            clearInterval(timer)
            timer = setInterval(() => {
                index.value++
                if (index.value >= props.sliders.length) {
                    index.value = 0
                }
            }, props.duration)
        }
        //如果有数据且开启自动播放则调用自动播放函数
        // immediate:true考虑数据不是动态获取的情况
        watch(() => props.sliders, (newVal) => {
            if (newVal.length && props.autoPlay) {
                autoPlayFn()
            }
        }, { immediate: true })

        // 鼠标移入时暂停
        const stop = () => {
            if (timer) clearInterval(timer)
        }
        // 鼠标移出时滚动
        const start = () => {
            if (props.sliders.length && props.autoPlay) {
                autoPlayFn()
            }
        }
        // 左侧箭头上一页切换,右侧箭头下一页切换
        const toggle = (step) => {
            const newIndex = index.value + step
            if (newIndex > props.sliders.length - 1) {
                return index.value = 0
            }
            if (newIndex < 0) {
                return index.value = props.sliders.length - 1
            }
            index.value = newIndex
        }
        return { index, stop, start, toggle }
    }
}
</script>
<style scoped lang="less">
.xtx-carousel {
    width: 100%;
    height: 100%;
    min-width: 300px;
    min-height: 150px;
    position: relative;

    .carousel {
        &-body {
            width: 100%;
            height: 100%;
        }

        &-item {
            width: 100%;
            height: 100%;
            position: absolute;
            left: 0;
            top: 0;
            opacity: 0;
            transition: opacity 0.5s linear;

            &.fade {
                opacity: 1;
                z-index: 1;
            }

            img {
                width: 100%;
                height: 100%;
            }
        }

        &-indicator {
            position: absolute;
            left: 0;
            bottom: 20px;
            z-index: 2;
            width: 100%;
            text-align: center;

            span {
                display: inline-block;
                width: 12px;
                height: 12px;
                background: rgba(0, 0, 0, 0.2);
                border-radius: 50%;
                cursor: pointer;

                ~span {
                    margin-left: 12px;
                }

                &.active {
                    background: #fff;
                }
            }
        }

        &-btn {
            width: 44px;
            height: 44px;
            background: rgba(0, 0, 0, .2);
            color: #fff;
            border-radius: 50%;
            position: absolute;
            top: 228px;
            z-index: 2;
            text-align: center;
            line-height: 44px;
            opacity: 0;
            transition: all 0.5s;

            &.prev {
                left: 20px;
            }

            &.next {
                right: 20px;
            }
        }
    }

    &:hover {
        .carousel-btn {
            opacity: 1;
        }
    }
}
</style>